DOJ Sues Denver and Colorado Over Gun Bans in Back-to-Back Federal Lawsuits

Mike Johnston said “hell no.” The Department of Justice said okay, see you in court.

That's roughly how the last 48 hours have played out in Colorado. On Monday, May 4, the Denver mayor stood on the steps of the City and County Building and rejected a DOJ demand letter calling for the city to repeal its 1989 “assault weapons” ordinance. By Tuesday afternoon, a federal lawsuit hit. By Wednesday afternoon, a second federal lawsuit landed — this one against the State of Colorado over the statewide ban on magazines holding more than 15 rounds.

Two federal lawsuits in two days, both targeting Colorado gun laws. If you live in Denver and own an AR-15-style rifle, or you've got a standard-capacity magazine in a safe somewhere in this state, this matters. Here's what's actually happening.

What the Denver Ordinance Actually Bans

Denver's ordinance has been on the books since 1989. It prohibits possession, sale, and transfer of “assault-style weapons” within city limits, defined in part by a magazine capacity threshold — guns capable of accepting more than 15 rounds in a detachable magazine. AR-15-style rifles fall squarely inside that definition.

This is older than most state-level bans. Most of the assault weapons bans on the books today came either after the 1994 federal AWB or in the post-Sandy Hook wave. Denver's predates the federal AWB by five years, and it's stayed in place ever since.

When the DOJ filed Tuesday, they came after the ordinance directly: it bans firearms in common use for lawful purposes — the kind owned by tens of millions of Americans — and that violates the Second Amendment under the framework the Supreme Court laid down in Bruen.

Quick Refresher on What Bruen Has to Do With Anything

For folks who haven't been tracking the case law: NYSRPA v. Bruen is the 2022 Supreme Court decision that threw out New York's century-old “may-issue” concealed carry permit scheme. More importantly for this fight, it set the framework for evaluating gun laws today. The government can't justify a regulation just by arguing it serves a public safety interest. The government has to show the regulation is “consistent with the Nation's historical tradition of firearm regulation.”

Translation: if you can't point to a comparable law from around 1791, when the Second Amendment was ratified, or 1868, when the Fourteenth Amendment incorporated it against the states, your gun law is on shaky ground.

The DOJ complaint leans hard on this. It quotes Justice Thomas calling “assault weapon” a rhetorically charged political term — the complaint actually calls the phrase a term “developed by anti-gun publicists” — and notes that AR-15-style rifles and the magazines that feed them are in common use across the country. There is no historical analogue for banning arms in common use. That's the whole game.

Colorado's Magazine Ban Just Got Hit Too

On Wednesday afternoon, the DOJ filed a second suit, this time against the state. The target: Colo. Rev. Stat. § 18-12-302, the law that makes it a crime to sell, transfer, or in many cases possess a magazine holding more than 15 rounds. Colorado passed this one in 2013 in the wake of the 2012 Aurora theater shooting.

Assistant Attorney General Harmeet Dhillon called the ban “political virtue signaling at the expense of Americans' constitutional right to keep and bear arms.” Colorado AG Phil Weiser — who's running for governor and won the Democratic primary in March — called the lawsuit a “dangerous overreach” and vowed to defend the law in court.

The Colorado Supreme Court already upheld the magazine ban back in 2020, but only against the state constitution, not the Second Amendment. The Tenth Circuit has never weighed in. Now it almost certainly will.

The “Hell, No” Press Conference

Mayor Johnston's Monday remarks weren't subtle. “We're here today to let them know that our answer is hell no,” he told reporters from the City and County Building steps. He invoked Columbine, Aurora, and Boulder, framing the ordinance as a “common-sense policy” that has kept “weapons of war” off Denver streets for 37 years.

Denver City Attorney Miko Brown's formal response letter called the DOJ demand “baseless, irresponsible, and a clear overreach of the federal government's power.” She also pointed out that six federal appellate courts — the First, Second, Fourth (en banc), Seventh, Ninth, and D.C. Circuits — have upheld assault weapons or magazine bans in the post-Bruen era. I guess the city attorney doesn't understand the 2nd amendment.

She's not wrong about the circuit count. What she didn't mention is that the Supreme Court hasn't taken up any of those cases yet, which is the only opinion that ultimately matters. That circuit count gets cited a lot in this debate. It tells you where the lower courts have landed. It doesn't tell you where the case law actually ends up.

The Awkward Part for Denver's Defense

Brown's letter cites a recent Tenth Circuit decision, U.S. v. Morgan, in which a three-judge panel unanimously upheld the federal machine gun ban. She uses it to argue that “common use” — the prevalence of an arm in private hands — doesn't decide Second Amendment cases. That's a defensible read of Morgan. It's also a different argument than the one the DOJ is making here. Machine guns post-1986 aren't in common civilian use. AR-15-style rifles are.

There's a separate awkwardness worth flagging: the DOJ's new Second Amendment Section, the unit running this litigation, is led by Barry Arrington. Arrington is a former Colorado state representative and former chief legal counsel for the National Association for Gun Rights. He sued Colorado over the magazine ban in 2022 from the outside. That suit was dismissed in 2024 — and Denver's response letter actually mentions it by name, citing it as evidence the magazine ban survives Second Amendment challenge.

Arrington now leads the federal government's case against Denver's AWB and Colorado's magazine ban from the inside. If you'd told me five years ago that DOJ would have an in-house Second Amendment Section run by an attorney who used to litigate against Colorado for gun rights organizations, I would have laughed. Here we are.

What This Means for Concealed Carriers Specifically

Direct effect on your CCW: zero, at least for now. Neither lawsuit touches concealed carry licensing, reciprocity, sensitive-place restrictions, or where you can legally carry your handgun. If you're a permit holder in Colorado, nothing about your day-to-day legal posture changed this week.

Indirect effect: significant. If the Tenth Circuit ends up ruling on either of these cases — or if the Supreme Court picks one up on appeal — the resulting decision will shape how every gun law in this circuit gets evaluated, including laws that affect handgun ownership, carry, and the gear you carry with. A clean federal Second Amendment win on either case would put a lot of other Colorado statutes on uncertain ground.

One thing to be clear about: if you live inside Denver city limits and you currently own a restricted rifle or a standard-capacity magazine, the lawsuit doesn't change your legal exposure. The DOJ is asking the court to enjoin enforcement. That hasn't happened. The ordinance is still in effect. So is the state magazine ban. Don't read the headlines and assume the law has changed yet — it hasn't.

Speaking of Colorado Gun Laws — There's More Going On

The Colorado General Assembly has been busy this year, and the 2026 session adjourns on May 13, one week from today. I'll do a full session recap after sine die. The short version for now:

Governor Polis has already signed an expansion of the Extreme Risk Protection Order law (SB26-004) and a ban on 3D-printed firearm manufacturing (HB26-1144). HB26-1126, which adds new requirements and security mandates for federally licensed firearm dealers, has cleared both chambers and is awaiting his signature. SB26-043 — a first-in-the-nation barrel registration scheme — has been stalled at House third reading since March 20, but the session isn't over yet.

On the pro-Second Amendment side, every meaningful bill died in committee on party-line votes. The Second Amendment Protection Act (HB26-1021) and a constitutional carry bill (HB26-1212) both got killed without ever reaching the floor.

I'll come back to all of this in detail after May 13. For now, the headline is: Colorado is making more gun law, the DOJ is suing Colorado over old gun law, and the next two weeks are going to be a lot.